Chemicals used in, for example, semiconductor device processing, are delivered into a process chamber using a fluid containing ampoule. Such known ampoules typically include a canister that is in fluid communication with an inlet port and an outlet port using a carrier gas that is fed through the ampoule. For example, the carrier gas is fed into a space above the fluid, may flow over the fluid, and carries away vapor from the space above the fluid. As another example, the carrier gas is fed into the fluid using a bubbler tube, saturates the fluid, and carries away some of the fluid. The ampoule may be used until all fluid is removed, at which time the ampoule is refilled or replaced. Alternatively, the ampoule may be refilled periodically based on measurements taken using an in situ level sensor. A refill tank holds chemicals for refilling the ampoule and typically has a much larger volume than the ampoule to enable the ampoule to be repeatedly refilled.
Some of the processes used in, for example, semiconductor device processing use one or more chemicals supplied to the process at defined temperature and pressure ranges. For example, a film deposition process may maintain temperature and pressure within predefined ranges to attain a repeatable film quality and consistent film thickness. However, as fluid is consumed in the ampoule, temperature and pressure conditions may change and therefore change the concentration of the chemical being delivered which affects the outcome of the process being carried out.
Accordingly, the inventors have provided improved apparatus and methods for regulating fluid chemical delivery.